1. Field of the Invention
The present invention relates to an electronic package incorporating a heat-generating element which is thermally coupled to a heat-sinking member, through the utilization of a predetermined thermally conductive material, and wherein all of these components are placed in compression during package operation so as to resultingly improve the thermal performance of the electronic package. Moreover, the invention is directed to a method of improving the thermal performance of an electronic package through the intermediary of compressive forces being generated between the package components during package operation.
In essence, the thermal performance of an electronic package, which may be constituted of a heat-generating element such as a semiconductor chip, and which is coupled to a heat-sinking member, such as a finned heat sink, or the like, may be implemented through the utilization of a specified thermally conductive material, and in which the thermal performance is governed by the highest thermal resistance present in the package. Quite frequently, this thermal resistance is encountered at the smallest area through which the heat which is generated must flow, and this typically occurs in a region or a gap between the chip dissipating the power and the heat sink, a cover plate or heat spreader. The resistance to heat flow in that direction is normally R=l/kA, where R represents the resistance in C/W, k is the thermal conductivity of the material present in the gap and l is the thickness of that material.
Pursuant to the inventive concept, compression between the various electronic package components can be provided through the use of a mechanical structure, such as springs or similar biasing elements imparting compression to the electronic package components, or through the employment of two adhesives possessing different coefficients of thermal expansion so as to, during operation of the electronic package, generate compressive forces improving the thermal performance of the electronic package.
2. Field of the Prior Art
The concept of employing compressive forces, and various methods of imparting such compressive forces to the components of electronic packages, is well-known in this technology.
Thus, U.S. Pat. No. 5,548,482, to Hatauchi et al., describes a module which is mechanically supported through the attachment thereof to a printed circuit board. The patent states that the supports for a card mounting the printed circuit board are attached by soldering, and thus, are able to support only limited stress above which the solder will tend to creep, especially at high operating temperatures. There is no clear disclosure of any method or structure to provide for the enhancement of the thermal performance of electronic packages analogous to that of the present invention.
U.S. Pat. No. 5,602,719, to Kinion, describes a structure to provide for electronic package level cooling, and not for chip levels, as disclosed by the present inventive concept. There is no disclosure of providing for an improved thermal performance through the intermediary of an adhesive and applied pressure during electronic package operation. There is only a disclosure of a thermal grease and no suggestion of utilizing an adhesive, such as preferably a thermal adhesive, as contemplated herein. Thermal grease tends to come out during operation because of package movement.
U.S. Pat. No. 5,022,462, to Flint et al., describes a flexible finned heat exchanger and is adapted to provide structure to replace TCM-like, multi-chip modules. Thermal enhancement is provided through the use of a grease, and not through an adhesive material, as provided by the present invention.
U.S. Pat. No. 5,581,442, to Morosas, describes a spring clip for clamping a heat sink module to an electronic module, and does not disclose the particular use of an adhesive, such as a thermal adhesive analogous to the present invention.
Similarly, U.S. Pat. No. 5,595,240, to Daikoku et al., also describes a cooling apparatus for electronic devices including a resilient spring structure located internally of a module, and there is no discussion of the effect of pressure acting on components of the electronic package to increase the thermal performance of the package through the use of an adhesive, such as a thermal adhesive.